The ultrathin gate oxides prepared by mechanical tensile-stress oxidation in the tilted cathode anodization system were studied. By bending the silicon wafer during the anodization process and releasing stress in the final stage, we applied mechanical tensile stress onto the silicon wafer to overcome the lattice mismatch between Si and SiO2. As a result of external mechanical stress in the gate oxide, different electrical characteristics of the metal-oxide-superconductor capacitors are discovered. Hatband voltages of the experimental samples with tensile-stress shift positively due to bandgap narrowing effect. It was observed that the quality and reliability of SiO2 grown by tensile-stress oxidation are significantly improved. (C) 2007 The Electrochemical Society.